I had done a similar comparison when the new Intel based iMacs were introduced.
From MacWorld New desktop machines leave no doubt about Mac’s price-competitiveness
If you caught the Mac Pro’s introduction during last week’s Worldwide Developers Conference keynote, you know that Phil Schiller, Apple’s senior vice president for worldwide product marketing, punctuated his demo of the new high-end desktop by uttering the “D” word—Dell. Specifically, Schiller brought up Dell to compare its price to the standard 2.66GHz Mac Pro Quad’s $2,499 price tag. By Schiller’s math, a similarly configured Dell Precision 690 would run you $3,448—around $950 more than the Mac Pro.